A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. including part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Conventional lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning” direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.
Plasma cleaning treatment may be used to remove particles, impurities and contaminants from the surface area of an object through the use of an energetic plasma created from gaseous species. Gases such as argon and oxygen, as well as mixtures such as air and hydrogen/nitrogen may be used. Such an energetic plasma may be created while ionizing a low pressure gas phase. The energetic, ionic gaseous species react with impurities and contaminants on the surface area of the object to be cleaned, often producing gaseous products which can be removed by a vacuum system. The energetic species also clean the surface area by collision with the surface area, knocking off the impurities and contaminants from the surface area. With conventional plasma cleaning treatment of an object having different levels of contamination, it may not be possible to achieve a high level of cleanliness, which may require separately and manually cleaning subassemblies of the object and the packing material. Furthermore, for example, hydrocarbons such as lubricants or oils which are present on the outer surface area of the object might create contamination for the plasma cleaning device itself. There also remains a risk of contamination during assembling the object and the packing material as a whole after the plasma cleaning treatment is carried out.